Aim: The purpose of the present study was to establish which type of exercise is optimal for Rectus Abdominis (RA) muscle, by measuring thickness and length changes using the extended field of view ultrasonography (EFOV US) during different conditions. The second purpose was to estimate the reliability of EFOV US as a muscle morphology assessment tool.
Material and methods: Segmental muscle thickness and length of 11 young healthy adults was assessed during 1) rest and isometric 2) trunk lifting, 3) leg lifting and 4) combined trunk and leg lifting exercises with the use of EFOV US.
Results: RA muscle thickness was significantly greater during exercises compared to rest (p<0.05). It was also observed that proximal and proximal-middle segments showed significantly less thickness and length compared to distal-middle and distal segments (p<0.05). Even though no differences in thickness were observed between the exercises, leg lifting and combined trunk and leg lifting exercises affected more the distal segment of RA muscle (p<0.05). Moreover, no significant differences in length between exercises was found (p>0.05). Further, EFOV US displayed excellent reliability as the ICC values ranged from 0.82 to 0.97.
Conclusions: According to our observations it seems that exercises that induce lifting of the legs might be more effective for the distal parts of RA muscle. EFOV appears to be a reliable diagnostic tool for measuring RA muscle thickness during rest and contracting states.